People who take a dopamine stimulator in combination with the dopamine precursor levodopa often experience drowsiness. In some cases, this is severe enough to induce sudden sleep, which may occur without warning. Patients are urged to be aware of this possibility, which is most likely to occur when beginning therapy, increasing dosage level or switching to a new dopamine stimulator.

Because dopamine stimulators can cause drowsiness, patients are urged to avoid certain  activities (e.g., driving, using machinery) until they know how these drugs are likely to affect them.

Some patients who take dopamine stimulators also may find themselves more likely to engage in compulsive behaviors, such as hypersexuality, compulsive gambling and compulsive overeating. Patients who experience such symptoms are urged to contact their physician.

Dopamine stimulators may cause additional side effects in patients who take them. These include:

• Abdominal pain
  
  
• Chest pain
  
  
• Confusion
  
  
• Depression
  
  
• Dry mouth
  
  
• Edema
  
  
• Hallucinations
  
  
• Headaches
  
  
• Nausea and vomiting
  
  
• Nightmares
  
  
• Low blood pressure (hypotension)
  
  
• Orthostatic hypotension (low blood pressure resulting from posture change)
  
  
• Psychosis
  
  
• Sleep problems

Some patients who take certain dopamine stimulators (e.g., pergolide, bromocriptine) may be at risk for developing fibrosis, a condition in which excess fibrous connective tissue develops in an organ. However, withdrawal of medication appears to reverse the symptoms of fibrosis for most patients.

Additionally, some patients who take bromocriptine or pergolide may experience inflammatory reactions of the lungs and heart valves. Recent studies have also linked cabergoline with the development of heart valve defects.

Patients who take dopamine stimulators are likely to experience a leveling off of side effects as their body gradually adapts to the drug.